Forget simple 2D physics. Why not add some fluid excitement to your game? LiquidFun is an easy to use physics simulator that includes fluid and soft body simulation.

The main thing about LiquidFun, a Google project in C++, is that it is an extension of the well known Box2D physics engine. It makes use of OpenGL and it can be built for Android, Linux, OSX and Windows. The team behind this open source project are clearly intending it for Android use and they would like you to include a tracking code so that they can find out how much effort to put into developing and tuning it further.

If you already know Box2D then you can already program general ridged body movement and now you can add to this particle models.

You can create particles that by default behave like a liquid but you can set other behaviours. For example a group of solid particles keeps other things outside on its surface and are good for implementing objects like balls. Powder particles scatter like dust. Spring particles behave as if they were joined by springs. Tensile particles have surface tension and viscous particles cling to one another to produce a sticky liquid - and so on.

If you want to see it in action, there is a video for that:

If, after seeing this video, you are not inspired to write something then I don't know what is going to get you moving. Of course it is "just" 2D physics and this restricts the gameplay but you can argue that this is a game category that has hardly been explored and there may be many simple but engaging 2D physics based games to be discovered. After all, what was the recent Flappy Bird phenomenon but a 2D physics game - and now you can have fluids!